MIDI hardware MIDECO Manuel utilisateur
MIDECO
64-outputs MIDI note decoder
USER MANUAL
Roman Sowa 2012
www.midi-hardware.com
1.Overview
Thank you for choosin MIDECO as your new MIDI-to-di ital converter. This short
manual will uide you throu h installation, and available settin s.
Main purpose of this board is to drive di ital inputs of your instrument lackin MIDI
control. Each MIDI note within selected ran e is converted to lo ic volta e at one of the
outputs. By default when a note starts playin , the output oes to 5V, and stays there as
lon the note is on. With note release volta e drops to 0.
You can choose any channel and any MIDI notes ran e that MIDECO will respond to.
This can be done usin user-friendly MIDI-learn function, or for advanced users - by
sendin proper MIDI System Exclusive messa es.
There are 4 headers, each with 16 outputs. You can connect any kind of di ital circuitry,
or drive low power devices like LEDs. It's not possible to drive coils, valves, motors, or
bulbs with MIDECO directly, you have to provide your own driver circuit in such case,
usually sin le transistor per output is enou h.
All user settin s are memorized in nonvolatile memory, takin power off does not reset
anythin to defaults, the settin s are kept as they were last entered.
2.Layout & Connections
Picture below explains all connections to MIDECO board. They are:
● MIDI input
● MIDI THRU
● Power Supply
● GND
● MIDI-learn header
● 64 di ital outputs
● 2 activity LEDs
MIDI input is connected
with screw terminals, so no special connectors or tolls are needed. MIDI DIN socket
should be connected directly, without any components or power in between. If chainin
more MIDECO boards, for example to have full 128 note display, you may simply
connect MIDI si nal between the 2 boards usin plain 2-wire cable, no socket is needed.
Whenever MIDI si nal is received by MIDECO, onboard activity LED blinks. If MIDI note
from the pro rammed ran e and channel is reco nized, both status LEDs blink.
Power supply should come from re ulated power supply ivin from 5 to 12V DC. If
MIDECO is about to drive LEDs directly, and re ularly most of the LEDs will be on, it's
recommended to supply the board with volta e no hi her than 6-7V.
Connectin power supply in reverse makes no dama e to the board.
2.1.Digital Outputs
Each of the 64 note outputs can drive standard 5V di ital lo ic circuit. Maximum current
is reduced by series 1k resistor, so nothin ets dama ed if it's accidentally shorted to
GND or 5V supply. This also means that MIDECO can drive LEDs directly, providin
about 3mA current to typical LED. Default positive lo ic (0V for note off, 5V for note on)
can be altered usin MIDI Sys-Ex, so you can connect LEDs with either common anode,
or common cathode.
2.2.MIDI THRU output
MIDI si nal is available at MIDI THRU output to chain more devices. As any MIDI THRU
circuit, it causes sli ht de radation of MIDI si nal, so after chainin 10 or so devices, it
may become difficult to assure reliable performance. Last devices in the chain may have
problems understandin MIDI correctly. MIDI-THRU option is iven mainly to connect
more MIDECO boards to ether, but you can always connect it to typical MIDI THRU DIN
socket, and add any kind of MIDI instrument there. To comply with MIDI standard, you
should connect GND at connector 2 of MIDI THRU socket. See layout dia ram for
details.
2.3.MIDI-learn input
MIDI-learn is the way to setup basic operation: MIDI channel and startin note. To use
learn mode, connect momentary, normally open switch to little 2-pin header on MIDECO
board marked as "SETUP". Whenever you press this button and send to MIDECO the
any
MIDI note, it will use as new lowest note for the ran e of 64 outputs, and will tune to
MIDI channel used.
3.User settings
After successful installation, you can set up the MIDI channel, startin note and polarity
of the outputs. To do so, apply power to MIDECO board, connect MIDI source to MIDI
IN, and MIDI-learn button to the "setup" header. Alternatively you may do all the
settin s via Sys-Ex usin any kind of Sys-Ex editor, for example MIDIOX.
There are 3 parameters to set:
1. MIDI channel
2. ran e of notes
3. outputs polarity
Only the first two settin s (channel and notes ran e) can be done both ways, via MIDI-
learn button and Sys-Ex. The polarity is accessible via Sys-Ex only.
The System Exclusive command's structure is as follows:
Sys-Ex header (F0), manufacturer ID (00 20 7A), device ID (05), command (01 or 04),
its parameters and Sys-Ex footer (F7). This is described in details here. All numbers are
represented in hexadecimal format.
3.1.Channel and range of notes
Channel and ran e of notes can be set by MIDI-learn button, or Sys-Ex. For example to
make MIDECO respond to your keyboard, push the MIDI-learn button momentarily, and
play the lowest note.
The same settin s via System Exclusive:
F0 00 20 7A 05 01 <channel> 01 <startnote> F7
where
<channel>
parameter is MIDI channel number in ran e 1-16 (01-10 in hex), and
<startnote>
is MIDI note number associated with lowest output. The ran e always
covers 64 notes startin from that one.
3.2.Outputs polarity re ersal
F0 00 20 7A 05 04 <polarity> F7
where
<polarity>
determines how active note is indicated at the outputs. If <polarity>
is
"00", note on means +5V and note off 0V. If
<polarity>
is "01", output note is reversed,
meanin 0V for note on, and note off is +5V.
3.3.Factory defaults
Send this Sys-Ex sequence to MIDECO to o back to default settin s:
F0 00 20 7A 05 01 01 01 24 F7 F0 00 20 7A 05 04 00 F7
MIDECO will respond then to note ran e C2-C7 (36-99 in MIDI note numbers) in
channel 1 with positive ates (off 0V, on 5V)
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